dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

kent-and@xxxxxxxxx wrote:
> > > > One thing to consider is more sophisticated dof mapping. It is worth
> > > > considering a special class to take care of this. This would be useful
> > > > for meshes with mixed cell/element types, parallel assembly and
> > > > computing sparsity patterns.
> > > Yes, we could create a separate class in src/fem/ that takes care of
> > > this. Name suggestions: NodeMap, NodeMapping, Nodes, Dofs, DofHandler,
> > > ...
> > What about DofHandler or DofManager? I see the class handling the dof
> > mapping, as well as generating sparsity patterns. I'll add something,
> > and start with a function for computing the number of non-zeroes per
> > matrix row (we're overestimating this at the moment substantially which
> > is giving me some memory problems).
> >
> > Garth
>
> You can consider the dof-handler used in SyFi/PyCC. It is not as fast as the
> nodemap generated by FFC, but it is very flexible. It works for any dofs
> I know.
>
> It is also only about 100 lines of code, using a STL map. You can find it
> in the file DofT.h

I'm working on this right now so I'll take a look at the SyFi handler. 
I'm planning to offer different possibilities for the mapping, and also 
to allow user to provide something for special problems if they wish. 
The current FFC mapping is about as fast as it gets for scalar valued 
equations. For vector-valued equations, it's not good for sparse assembly.

Garth




> Kent